Solid-state imaging device, manufacturing method thereof, and electronic device

ABSTRACT

The present technology relates to a solid-state imaging device, a manufacturing method, and an electronic device, which can improve sensitivity while improving color mixing. The solid-state imaging device includes a first wall provided between a pixel and a pixel arranged two-dimensionally to isolate the pixels, in which the first wall includes at least two layers including a light shielding film of a lowermost layer and a low refractive index film of which refractive index is lower than the light shielding film. The present technology can be applied to, for example, a solid-state imaging device, an electronic device having an imaging function, and the like.

TECHNICAL FIELD

The present technology relates to a solid-state imaging device, amanufacturing method thereof, and an electronic device, and moreparticularly, the present technology relates to a solid-state imagingdevice, a manufacturing method thereof, and an electronic device capableof improving sensitivity while improving color mixing.

BACKGROUND ART

In a solid-state imaging device such as a CMOS image sensor, lightincident on an on-chip lens (microlens) of any given pixel obliquelyenters into an adjacent pixel, thereby causing color mixing. Therefore,for example, in the solid-state imaging device of Patent Document 1, astructure is proposed in which color mixing is prevented by providing apartition wall between color filters of adjacent pixels and betweenmicrolenses.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-251292

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, simply making the partition wall higher between the pixelsimproves color mixing, but the sensitivity is greatly reduced.

The present technology has been made in view of such a situation, and isto improve the sensitivity while improving the color mixing.

Solutions to Problems

A solid-state imaging device according to a first aspect of the presenttechnology includes a first wall provided between a pixel and a pixelarranged two-dimensionally to isolate the pixels, in which the firstwall includes at least two layers including a light shielding film of alowermost layer and a low refractive index film of which refractiveindex is lower than the light shielding film.

In a manufacturing method of a solid-state imaging device according to asecond aspect of the present technology, a first wall is formed betweena pixel and a pixel arranged two-dimensionally to isolate the pixels,and the first wall includes at least two layers including a lightshielding film of a lowermost layer and a low refractive index film ofwhich refractive index is lower than the light shielding film.

An electronic device according to a third aspect of the presenttechnology includes a solid-state imaging device including a first wallprovided between a pixel and a pixel arranged two-dimensionally toisolate the pixels, in which the first wall includes at least two layersincluding a light shielding film of a lowermost layer and a lowrefractive index film of which refractive index is lower than the lightshielding film.

In the first to third aspects of the present technology, a first wall isformed between a pixel and a pixel arranged two-dimensionally to isolatethe pixels, and the first wall includes at least two layers including alight shielding film of a lowermost layer and a low refractive indexfilm of which refractive index is lower than the light shielding film.

The solid-state imaging device and the electronic device may be anindependent device or a module incorporated in another device.

Effects of the Invention

According to the first to third aspects of the present technology,sensitivity can be improved while improving color mixing.

It should be noted that the effects described herein are not necessarilylimited, and any of the effects described in the present disclosure maybe applied.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for explaining a problem of an optical path colormixing.

FIG. 2 is a diagram for explaining a problem of an optical path colormixing.

FIG. 3 is a diagram for explaining a problem of an optical path colormixing.

FIG. 4 is a diagram showing a schematic configuration of a solid-stateimaging device to which the present technology is applied.

FIG. 5 is a cross-sectional view showing a pixel structure according toa first embodiment.

FIG. 6 is a diagram for explaining the refractive index of the firstwall.

FIG. 7 is a diagram for explaining a manufacturing method (firstmanufacturing method) of a pixel according to the first embodiment.

FIG. 8 is a cross-sectional view of pixels showing a modification of thepixel structure according to the first embodiment.

FIG. 9 is a cross-sectional view showing a pixel structure of a secondembodiment.

FIG. 10 is a figure showing relationship between the refractive indexesof the first wall and a second wall.

FIG. 11 is a figure for explaining a manufacturing method (secondmanufacturing method) of a pixel according to the second embodiment.

FIG. 12 is a cross-sectional view of pixels showing a first modificationof the pixel structure according to the second embodiment.

FIG. 13 is a cross-sectional view of pixels showing a secondmodification of the pixel structure according to the second embodiment.

FIG. 14 is a cross-sectional view showing a pixel structure of a thirdembodiment.

FIG. 15 is a figure showing relationship between the refractive indexesof the first wall, the second wall, and the like.

FIG. 16 is a figure for explaining a manufacturing method (thirdmanufacturing method) of a pixel according to the third embodiment.

FIG. 17 is a cross-sectional view of pixels showing a modification ofthe pixel structure according to the third embodiment.

FIG. 18 is an optical simulation result verifying the effect of thefirst wall and the second wall.

FIG. 19 is a block diagram showing a configuration example of an imagingdevice serving as an electronic device to which the present technologyis applied.

FIG. 20 is a figure for explaining an example of use of a solid-stateimaging device in FIG. 4.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a mode (hereinafter referred to as “embodiment”) forimplementing the present technology will be described. Furthermore, thedescription will be given in the following order.

-   1. Problems of optical path color mixing of solid-state imaging    device-   2. Schematic configuration example of solid-state imaging device-   3. Pixel structure of first embodiment (configuration example having    first wall)-   4. Manufacturing method of pixel structure according to first    embodiment-   5. Modification of pixel structure according to first embodiment-   6. Pixel structure according to second embodiment (first    configuration example having first wall and second wall)-   7. Manufacturing method of pixel structure according to second    embodiment-   8. Modification of pixel structure according to second embodiment-   9. Pixel structure of third embodiment (second configuration example    having first wall and second wall)-   10. Manufacturing method of pixel structure according to third    embodiment-   11. Modification of pixel structure according to third embodiment-   12. Actions and effects of first wall and second wall-   13. Application example to electronic device

<1. Problems of Optical Path Color Mixing of Solid-State Imaging Device>

First, problems of optical path color mixing associated with asolid-state imaging device such as a CMOS image sensor will be explainedwith reference to FIG. 1 to FIG. 3.

Generally, for example, color filters of red (R), green (G), or blue (b)are arranged by a Bayer arrangement or the like in each pixel repeatedlyformed in an array in the row direction and the column direction in asolid-state imaging device, and each pixel is configured to receivelight of a different wavelength (color).

In order for each pixel to attain specific spectroscopy, a color filteris required to have a certain film thickness. In addition, in order tosatisfy the convergence, the on-chip lens is required to have a certainlens height. Therefore, for example, in order to improve imageresolution, as shown in FIG. 1, in a case where the pixel size isreduced, the aspect ratio which is the ratio between the horizontaldirection and the depth direction of pixel is deteriorated, and thelight incident on an on-chip lens 303 of the pixel in which a G colorfilter 302 is disposed exceeds an inter-pixel light shielding film 301formed at the pixel boundary and is incident on an R color filter 302 ofthe adjacent pixel, and optical path color mixing occurs.

In addition, even in a case where the pixel size is not changed, asshown in FIG. 2, a larger lens height of the on-chip lens 303 causesmore oblique light to leak into the adjacent pixels, and therefore,optical path color mixing also occurs in this case.

Furthermore, in the relationship between a CMOS image sensor chip 305and a condenser lens 306 shown in FIG. 3, the use of the condenser lens306 whose distance (pupil distance) from the condenser lens 306 to theCMOS image sensor chip 305 is shortened will increase the incident angleof the principal ray of the incident light in the peripheral portion ofthe CMOS image sensor chip 305. As a result, incident light is likely toenter into adjacent pixels, and shading occurs in which the peripheralportion of the CMOS image sensor chip 305 becomes darker than thecentral portion.

Pupil correction that deviates the center of the light receiving regionof each pixel from the center of the on-chip lens can improve shading ofoblique incident light but cannot correct shading of scattered lightsufficiently.

Optical path color mixing can be improved by forming the height of theinter-pixel light shielding film 301 to be high, for example, as high asthe film thickness of the color filter 302, but the sensitivity isgreatly reduced.

Therefore, in the following description, a solid-state imaging deviceadopting a pixel structure that improves sensitivity while improvingcolor mixing will be explained.

<2. Schematic Configuration Example of Solid-State Imaging Device>

FIG. 4 shows a schematic configuration of a solid-state imaging deviceto which the present technology is applied.

The solid-state imaging device 1 of FIG. 4 has a pixel array unit 3 inwhich pixels 2 are two-dimensionally arranged in a matrix on asemiconductor substrate 12 using, for example, silicon (Si) as asemiconductor, and a peripheral circuit unit therearound. The peripheralcircuit unit includes a vertical driving circuit 4, a column signalprocessing circuit 5, a horizontal driving circuit 6, an output circuit7, a control circuit 8, and the like.

The pixel 2 includes a photodiode as a photoelectric conversion unit anda plurality of pixel transistors. The plurality of pixel transistorsinclude, for example, four MOS transistors, i.e., a transfer transistor,a selection transistor, a reset transistor, and an amplificationtransistor.

In addition, the pixel 2 can also have a shared pixel structure. Thisshared pixel structure includes a plurality of photodiodes, a pluralityof transfer transistors, one shared floating diffusion (floatingdiffusion region), and one other shared pixel transistor. Morespecifically, in the shared pixel structure, photodiodes and transfertransistors constituting a plurality of unit pixels share one otherpixel transistor.

The control circuit 8 receives an input clock, data instructing anoperation mode and the like, and outputs data such as internalinformation of the solid-state imaging device 1. More specifically, onthe basis of a vertical synchronization signal, a horizontalsynchronization signal, and a master clock, the control circuit 8generates clock signals and control signals which are the basis ofoperations of the vertical driving circuit 4, the column signalprocessing circuit 5, the horizontal driving circuit 6 and the like.Then, the control circuit 8 outputs the generated clock signal andcontrol signal to the vertical driving circuit 4, the column signalprocessing circuit 5, the horizontal driving circuit 6, and the like.

The vertical driving circuit 4 is constituted by, for example, a shiftregister, and selects a predetermined pixel driving wire 10 to supply apulse for driving the pixel 2 to the selected pixel driving wire 10, anddrives the pixels 2 in units of rows. More specifically, the verticaldriving circuit 4 sequentially selects and scans the pixels 2 of thepixel array unit 3 in the vertical direction in units of rows, andsupplies a pixel signal based on the signal charge generated accordingto the amount of received light in the photoelectric conversion unit ofeach pixel 2 to the column signal processing circuit 5 through avertical signal line 9.

The column signal processing circuit 5 is arranged for each column ofpixels 2 and performs, for each pixel column, signal processing such asdenoising of the signal output from the pixels 2 in one row. Forexample, the column signal processing circuit 5 performs signalprocessing such as Correlated Double Sampling (CDS) and AD conversionfor removing pixel unique fixed pattern noise.

The horizontal driving circuit 6 is constituted by, for example, a shiftregister, and sequentially selects each of the column signal processingcircuits 5 by sequentially outputting horizontal scanning pulses, andoutputs a pixel signal from each of the column signal processingcircuits 5 to a horizontal signal line 11.

The output circuit 7 performs signal processing on the signalssequentially supplied from each of the column signal processing circuits5 through the horizontal signal line 11 and outputs the signals. Forexample, the output circuit 7 may only perform buffering, or may performblack level adjustment, column variation correction, various digitalsignal processing, and the like in some cases. An input and outputterminal 13 exchanges signals with the outside.

The solid-state imaging device 1 configured as described above is a CMOSimage sensor having a column ADC structure in which a column signalprocessing circuit 5 performing CDS processing and AD conversionprocessing is arranged for each pixel column.

<3. Pixel Structure of First Embodiment>

FIG. 5 is a cross-sectional view showing the pixel structure of thefirst embodiment adopted as the structure of the pixel 2 of thesolid-state imaging device 1.

The semiconductor substrate 12 includes, for example, silicon (Si) andis formed to have a thickness of, for example, 1 to 6 μm. In thesemiconductor substrate 12, for example, an N-type (second conductivitytype) semiconductor region 42 is formed in a P-type (first conductivitytype) semiconductor region 41 for each pixel 2 so that photodiodes PDare formed in units of pixels.

The upper side of FIG. 5 is the backside of the semiconductor substrate12 to which light is incident, and the lower side of FIG. 5 is the frontside of the semiconductor substrate 12 on which pixel transistors (notshown) and multilayer wiring layers are formed. Therefore, thesolid-state imaging device 1 adopting the pixel structure of FIG. 5 is aback-illuminated CMOS image sensor in which light enters from thebackside of the semiconductor substrate 12.

At the boundary portion between the adjacent pixels 2 on the substrateof the backside of the semiconductor substrate 12 which is the upperside in the figure, a light shielding film 43 for preventing theincident light from leaking into the adjacent pixel is formed, and afirst low refractive index film 44 and a second low refractive indexfilm 45 having a refractive index lower than that of the light shieldingfilm 43 are laminated on the light shielding film 43.

The material constituting the light shielding film 43 may be of anymaterial as long as the material blocks light. For example, a metal filmof tungsten (W), aluminum (Al), copper (Cu) or the like or an oxidizedfilm thereof can be used. Furthermore, the material constituting thelight shielding film 43 maybe an organic resin material internallycontaining a carbon black pigment or a titanium black pigment.

Furthermore, the light shielding film 43 is formed by stacking aplurality of metal films. For example, the light shielding film 43 mayinclude a laminated structure including tungsten (W) formed with a filmthickness of about 200 nm as a lower layer and titanium (Ti) formed witha film thickness of about 30 nm as an upper layer.

The first low refractive index film 44 and the second low refractiveindex film 45 may include, for example, an inorganic film such as SiN,SiO₂, SiON, and a resin material (organic film) such as a styrene resin,an acrylic resin, a styrene-acrylic copolymer resin, or a siloxaneresin.

In the present embodiment, the first low refractive index film 44includes, for example, SiN formed with a film thickness of about 50 nm,and the second low refractive index film 45 includes SiO₂ formed with afilm thickness of about 550 nm, for example.

Furthermore, in the following description, the three layers of the lightshielding film 43, the first low refractive index film 44, and thesecond low refractive index film 45 are collectively referred to as afirst wall 50, and the first wall 50 at the boundary portion between theadjacent pixels separates the pixels. For example, the height of thefirst wall 50 is set within a range of 50 to 2000 nm, and the width ofthe first wall 50 is set within a range of 50 to 300 nm, which isappropriately set according to the pixel size and the like.

In addition, the laminated surface of the first wall 50 and the backsideupper surface of the semiconductor substrate 12 not having the firstwall 50 formed thereon are covered with a protective film 46 such as Sioxide film. The protective film 46 is a film for preventing corrosion,and can be formed with a film thickness of, for example, about 50 to 150nm, but it is not always necessary to form the protective film 46.

A color filter 47 of any one of red (R), green (G), or blue (B) isformed above the photodiode PD on the backside of the semiconductorsubstrate 12 with the protective film 46 interposed therebetween. Theheight (film thickness) of the color filter 47 and the height of thefirst wall 50 are formed to be the same. In a case where the protectivefilm 46 is formed, the combined height of the protective film 46 and thefirst wall 50 and the height of the color filter 47 are formed to be thesame.

On the upper side of the layer of the first wall 50 and the color filter47, an on-chip lens 48 is formed for each pixel 2. The on-chip lens 48includes a resin material such as a styrene resin, an acrylic resin, astyrene-acrylic copolymer resin, or a siloxane resin, for example. Theincident light is condensed by the on-chip lens 48, and the condensedlight is efficiently incident on the photodiode PD via the color filter47. In addition, an antireflection film 49 is formed on the surfacelayer of the on-chip lens 48.

FIG. 6 shows the refractive index of the first wall 50.

Of the light shielding film 43, the first low refractive index film 44,and the second low refractive index film 45, the second low refractiveindex film 45 closest to the on-chip lens 48 is the film having thelowest refractive index. The refractive index increases as gettingcloser to the semiconductor substrate 12 in the following order: thefirst low refractive index film 44, and the shielding film 43.

Specifically, in a case where the second low refractive index film 45includes SiO₂, the first low refractive index film 44 includes SiN, andthe light shielding film 43 includes atitanium/tungsten (Ti/W) doublelayer structure, the refractive index of the second low refractive indexfilm 45 is about 1.5, the refractive index of the first low refractiveindex film 44 is about 1.7, and the refractive index of the lightshielding film 43 is about 2.7.

Note that the refractive indexes of the first low refractive index film44 and the second low refractive index film 45 are appropriately setwithin a range of about 1.00 to 1.70, for example, according to thepixel size and the like.

The refractive index of the on-chip lens 48 can be appropriately setwithin the range of 1.50 to 2.0, but the refractive index of the on-chiplens 48 is, for example, about 1.55 to 1.60 in the example of FIG. 6.

In this manner, on the light shielding film 43 formed at the boundary ofeach pixel 2 two-dimensionally arranged in the pixel array unit 3, thelow refractive index films (first low refractive index film 44 andsecond low refractive index film 45) having lower refractive indexesthan the light shielding film 43 are stacked, so that it is possible toimprove the sensitivity while suppressing color mixing. The degree ofimprovement of color mixing level and sensitivity level in the pixelstructure according to the present technology will be described laterwith reference to FIG. 18 together with other pixel structures describedlater.

<4. Manufacturing Method of Pixel Structure According to FirstEmbodiment>

A manufacturing method (first manufacturing method) of the pixel 2according to the first embodiment will be explained with reference toFIG. 7.

First, as shown in A of FIG. 7, the light shielding film 43, the firstlow refractive index film 44, and the second low refractive index film45 are sequentially formed on the backside upper surface of thesemiconductor substrate 12 on which the photodiode PD is formed.

As described above, for example, the light shielding film 43 includestwo layers of metal films having titanium (Ti) having a film thicknessof about 30 nm as an upper layer and tungsten (W) having a filmthickness of about 200 nm as a lower layer. The first low refractiveindex film 44 includes, for example, SiN formed with a film thickness ofabout 50 nm and the second low refractive index film 45 includes SiO₂formed with a film thickness of about 550 nm, for example.

Next, as shown in B of FIG. 7, a photoresist 81 with a film thickness ofabout 630 nm is coated on the upper surface of the second low refractiveindex film 45, and as shown in C of FIG. 7, by lithography technique,the photoresist 81 is patterned so that only the pixel boundary portionis left with a width of about 150 to 200 nm.

Then, as shown in D of FIG. 7, by performing dry etching processing onthe basis of the patterned photoresist 81, the light shielding film 43,first low refractive index film 44, and second low refractive index film45 are removed until the backside upper surface of the semiconductorsubstrate 12 is exposed. Thereafter, the photoresist 81 is removed, andthe protective film 46 such as Si oxide film is formed on the entiresurface. The film thickness of the protective film 46 is, for example,about 50 nm.

Next, as shown in E of FIG. 7, the color filter 47 is formed on theupper surface of the semiconductor substrate 12 above the photodiode PDin a predetermined RGB arrangement such as a Bayer arrangement.

Next, as shown in F of FIG. 7, the on-chip lens 48 is formed on theupper side of the color filter 47, and the antireflection film 49 isformed on the surface of the on-chip lens 48. The on-chip lens 48 can beformed, for example, by patterning a photosensitive resin material by alithography technique and then deforming the photosensitive resinmaterial into a lens shape by reflow processing. Alternatively, theon-chip lens 48 maybe formed by an etch-back method.

As a result of the above steps, the pixel 2 of the pixel structure shownin FIG. 5 is completed.

<5. Modification of Pixel Structure of First Embodiment>

FIG. 8 is a cross-sectional view of pixels 2 showing a modification ofthe pixel structure according to the first embodiment. In FIG. 8, theparts corresponding to FIG. 5 are denoted with the same referencenumerals, and the description about those parts is omitted.

In the pixel structure shown in FIG. 5, the first wall 50 included threelayers including the light shielding film 43, the first low refractiveindex film 44, and the second low refractive index film 45. In the pixel2 of FIG. 8, the first low refractive index film 44 is omitted, and thefirst wall 50 includes two layers including the light shielding film 43and the second low refractive index film 45.

As described above, the first wall 50 may include two layers includingthe light shielding film 43 of the lowermost layer. In this case, also,the refractive index of second low refractive index film 45 is about1.5, and the refractive index of light shielding film 43 is about 2.7.Therefore, the first wall 50 is formed so that the refractive indexincreases sequentially from the on-chip lens 48 to the semiconductorsubstrate 12.

In addition, the first wall 50 may include three or more layersincluding the lowermost light shielding film 43, and also in that case,the first wall 50 is formed so that the refractive index increasessequentially from the on-chip lens 48 to the semiconductor substrate 12.

<6. Pixel Structure of Second Embodiment>

FIG. 9 is a cross-sectional view showing a pixel structure of a secondembodiment adopted as the structure of a pixel 2 of a solid-stateimaging device 1.

In FIG. 9, the parts corresponding to the first embodiment describedabove are denoted with the same reference numerals, and the descriptionabout those parts is omitted as necessary.

In the second embodiment, on the upper side of a first wall 50, a secondwall 100 is further formed so as to separate an on-chip lens 48 of eachpixel 2. As shown in FIG. 9, the cross-sectional shape of the secondwall 100 is a reverse trapezoid (inverse tapered) shape in which thewidth of the top where the light enters is the widest and the widthbecomes thinner toward a semiconductor substrate 12. Alternatively, thecross-sectional shape of the second wall 100 may have a shape in whichthe top width and the bottom width at the first wall 50 aresubstantially the same width.

FIG. 10 shows a relationship between the refractive index of the firstwall 50 and the refractive index of the second wall 100.

The material of the second wall 100 is selected so that the refractiveindex of the second wall 100 is within the range of, for example, about1.2 to 1.7 and lower than a second low refractive index film 45 of thefirst wall 50. In addition, the material of the second wall 100 isselected so that the refractive index is lower than the adjacent on-chiplens 48.

The material of the second wall 100 includes, for example, an oxidizedfilm (inorganic film) such as SiO₂, and a highly transparent resinmaterial (organic film) such as a styrene resin, an acrylic resin, astyrene-acrylic copolymer resin, or a siloxane resin.

For example, as shown in FIG. 10, when it is assumed that: therefractive index of the second low refractive index film 45 of the firstwall 50 is about 1.5; the refractive index of a first low refractiveindex film 44 is about 1.7; the refractive index of a light shieldingfilm 43 is about 2.7, then, the second wall 100 is formed using anorganic material having a refractive index of about 1.2.

Even in a case where the entire two walls including the first wall 50and the second wall 100 is considered, the first wall 50 and the secondwall 100 are arranged so that the refractive index increasessequentially from the on-chip lens 48 to the semiconductor substrate 12.Incidentally, the refractive index of the on-chip lens 48 is, forexample, about 1.55 to 1.60 in a similar manner as the first embodiment.

In this manner, the first wall 50 of the same layer as a color filter 47and the second wall 100 formed in the layer of the on-chip lens 48 areformed on the boundary portion of each pixel 2 two-dimensionallyarranged in a pixel array unit 3 with a low refractive index film havinga low refractive index, so that the sensitivity can be improved whilesuppressing color mixing.

<7. Manufacturing Method of Pixel Structure of Second Embodiment>

A manufacturing method (second manufacturing method) of a pixel 2according to the second embodiment will be described with reference toFIG. 11.

The process up to the formation of the first wall 50 and the colorfilter 47 on the backside upper surface of the semiconductor substrate12 on which a photodiode PD is formed is similar to the firstmanufacturing method described with reference to A to E of FIGS. 7.

Then, as shown in A of FIG. 11, an on-chip lens material 121 is appliedto the upper surface of the first wall 50 formed on the backside uppersurface of the semiconductor substrate 12 and the color filter 47, sothat the on-chip lens material 121 has a film thickness equivalent tothe second wall 100 formed later, i.e., a film thickness of about 500 nmcorresponding to the residual film after on-chip lens 48 lens formation.

Next, as shown in B of FIG. 11, a photoresist 122 is coated on theentire surface with a film thickness of about 620 nm. Of the entiresurface, the pixel boundary portion corresponding to the formationposition of the second wall 100 is patterned and opened with a width ofabout 150 nm.

Then, as shown in C of FIG. 11, by performing dry etching processing onthe basis of the patterned photoresist 122, the on-chip lens material121 under the opening is removed, and an on-chip lens layer 124 and agroove portion 123 having the same height as the second wall 100 areformed.

Note that the on-chip lens layer 124 and the groove portion 123 may beformed as follows: in a manner similar to a third manufacturing methoddescribed below with reference to A and B of FIG. 16, a photosensitiveresin material is used as the on-chip lens material 121, and a regionother than the groove portion 123 is exposed and cured.

Next, as shown in D of FIG. 11, a low refractive index organic material125 which is to be the second wall 100 is applied to the groove portion123 between the on-chip lens layers 124 so that the low refractive indexorganic material 125 is sufficiently embedded therein. Through thisapplication step, the organic material 125 is also applied to the uppersurface of the on-chip lens layer 124. Therefore, next, the organicmaterial 125 formed on the top surface of the on-chip lens layer 124 isremoved by etch-back processing or chemical mechanical polishing (CMP).As a result, as shown in E of FIG. 11, the second wall 100 is completed.

Thereafter, the on-chip lens material 121 is applied again to the uppersurface of the on-chip lens layer 124 and the second wall 100, and thecoated on-chip lens material 121 is formed into a lens shape by reflowprocessing or etch-back method, so that the on-chip lens 48 includingthe previously formed on-chip lens layer 124 is formed as shown in F ofFIG. 11, and an antireflection film 49 is formed on the surface of theon-chip lens 48.

As a result of the above steps, the pixel 2 of the pixel structure shownin FIG. 9 is completed.

<8. Modification of Pixel Structure of Second Embodiment>

FIG. 12 is a cross-sectional view of pixels 2 showing a firstmodification of the pixel structure according to the second embodiment.In FIG. 12, the parts corresponding to FIG. 9 are denoted with the samereference numerals, and the description about those parts is omitted asnecessary.

In the modification of the second embodiment shown in FIG. 12, like themodification of the first embodiment, the first low refractive indexfilm 44 is omitted in the first wall 50, and the first wall 50 includestwo layers including the light shielding film 43 and the second lowrefractive index film 45.

In the second embodiment, the first wall 50 may also include a pluralityof layers as long as the first wall 50 includes two or more layersincluding the light shielding film 43 of the lowermost layer. Inaddition, the second wall 100 may include a plurality of layers insteadof one layer. In the first wall 50 and the second wall 100 as a whole,each layer constituting the first wall 50 and the second wall 100 islayered so that the refractive index increases sequentially from theon-chip lens 48 to the semiconductor substrate 12.

In addition, in the pixel structure of the second embodiment shown inFIG. 9, a material having a refractive index of about 1.55 to 1.60 isused as the material of the on-chip lens 48, whereas in the modificationof the second embodiment of FIG. 12, a material having a refractiveindex of about 1.60 to 2.00, which is higher than that, is adopted. Byusing a material having a high refractive index as the material of theon-chip lens 48 in this manner, the difference in refractive index fromthe second wall 100 is increased, and color mixing can be furthersuppressed. Incidentally, also in the first embodiment described above,it is possible to use a material having a high refractive index as thematerial of the on-chip lens 48.

FIG. 13 is a cross-sectional view of pixels 2 showing a secondmodification of the pixel structure according to the second embodiment.In FIG. 13, the parts corresponding to FIG. 9 are denoted with the samereference numerals, and the description about those parts is omitted asnecessary.

When the pixel structure of the second modification of the secondembodiment shown in FIG. 13 and the pixel structure of the secondembodiment shown in FIG. 9 are compared, the pixel structure of thesecond modification of the second embodiment shown in FIG. 13 isdifferent from the pixel structure of the second embodiment shown inFIG. 9 in that the cross sectional shape of the light shielding film 43is a trapezoidal shape having a wider bottom width than the top width.In addition, the height (film thickness) of the color filter 47 isformed to be higher than the first wall 50, and in the portion higherthan the first wall 50, the color filter 47 is in a tapered shape inwhich the peripheral portion is inwardly inclined. The cross-sectionalshape of the color filter 47 and the light shielding film 43 may havesuch a tilted shape depending on the film thickness to be set. There maybe a structure in which the shapes of the color filter 47 and the lightshielding film 43 shown in FIG. 13 are appropriately combined with thestructures of the other embodiments described above or described later.

<9. Pixel Structure of Third Embodiment>

FIG. 14 is a cross-sectional view showing a pixel structure of a thirdembodiment adopted as the structure of a pixel 2 of a solid-stateimaging device 1.

In FIG. 14, the parts corresponding to the first and second embodimentsdescribed above are denoted with the same reference numerals, and thedescription about those parts is omitted as necessary.

In the third embodiment, a second wall 100 is provided on a first wall50 in a manner similar to the second embodiment shown in FIG. 9. Inaddition, a high refractive index layer 141 is formed in a region of thesame layer region as the second wall 100 on the upper side of a colorfilter 47. For example, a photosensitive transparent resist or the likehaving photosensitivity and having a transmittance of 90% or more isused as the material of the high refractive index layer 141. Inaddition, an on-chip lens 48 and an antireflection film 49 using amaterial having a still higher refractive index than that of the highrefractive index layer 141 are formed on the upper side of the layerincluding the high refractive index layer 141 and the second wall 100.

FIG. 15 shows the refractive indexes of the first wall 50 and the secondwall 100, the color filter 47, the high refractive index layer 141, andthe on-chip lens 48.

Like the second embodiment, the first wall 50 and the second wall 100are formed such that the refractive index increases sequentially fromthe on-chip lens 48 to a semiconductor substrate 12.

Specifically, for example, the first wall 50 and the second wall 100 areformed such that the refractive index of the second wall 100 is about1.2, the refractive index of a second low refractive index film 45 ofthe first wall 50 is about 1.5, the refractive index of a first lowrefractive index film 44 is about 1.7, and a light shielding film 43 isformed to have a refractive index of about 2.7.

On the other hand, the color filter 47, the high refractive index layer141, and the on-chip lens 48 are formed such that the refractive indexincreases sequentially from the semiconductor substrate 12 to theon-chip lens 48.

Specifically, for example, the refractive index of the color filter 47is about 1.5, the refractive index of the high refractive index layer141 is about 1.8, and the refractive index of the on-chip lens 48 isabout 1.85.

As described above, a region of the same layer as the second wall 100 ismade into the high refractive index layer 141, so that the difference inthe refractive index from the adjacent second wall 100 increases and theleakage of incident light to the adjacent pixel can be still moreprevented.

<10. Manufacturing Method of Pixel Structure According to ThirdEmbodiment>

A manufacturing method (third manufacturing method) of a pixel 2according to the third embodiment will be described with reference toFIG. 16.

The process up to the formation of the first wall 50 and the colorfilter 47 on the backside upper surface of the semiconductor substrate12 on which a photodiode PD is formed is similar to the firstmanufacturing method described with reference to A to E of FIG. 7.

In addition, as shown in A of FIG. 16, a photosensitive transparentresist 151 which is a material of the high refractive index layer 141 iscoated on the upper surfaces of the first wall 50 and the color filter47 formed on the backside upper surface of the semiconductor substrate12 with a film thickness of, for example, about 500 nm according to theheight (film thickness) of the second wall 100 to be formed later. Inaddition, a photoresist 152 with a width of about 150 nm is patterned atthe pixel boundary portion corresponding to the formation position ofthe second wall 100, and the photosensitive transparent resist 151 onthe color filter 47 is cured. Thereafter, by removing the photoresist152 and the underlying photosensitive transparent resist 151, the highrefractive index layer 141 and a groove portion 153 are formed as shownin B of FIG. 16.

Next, as shown in C of FIG. 16, an organic material 125 having the lowrefractive index which is to be the second wall 100 is applied to thegroove portion 153 between the high refractive index layers 141 so thatthe organic material 125 is sufficiently embedded in the groove portion153 between the high refractive index layers 141. Thereafter, theorganic material 125 on the upper surface of the high refractive indexlayer 141 is removed by etch-back processing or CMP. As a result, asshown in D of FIG. 16, the second wall 100 is formed between the highrefractive index layers 141.

In addition, as shown in E of FIG. 16, an on-chip lens material 121 isapplied to the upper surfaces of the high refractive index layer 141 andthe second wall 100, and a photoresist 154 is formed into a lens shapeon the further upper surface. By using the lens shaped photoresist 154as a mask, the lens shape is transferred to the underlying on-chip lensmaterial 121 by dry etching method, so that as shown in F of FIG. 16,the on-chip lens 48 is formed. Finally, the antireflection film 49 isformed on the surface of the on-chip lens 48.

As a result of the above steps, the pixel 2 of the pixel structure shownin FIG. 14 is completed.

In the above third manufacturing method, the photosensitive transparentresist 151 is used as the material of the high refractive index layer141. In this case, the process of C in FIG. 11 in which the on-chip lensmaterial 121 is etched to form a groove portion 123 in the secondmanufacturing method can be eliminated, so that the manufacture of thesecond wall 100 becomes easier.

<11. Modification of Pixel Structure of Third Embodiment>

FIG. 17 is a cross-sectional view of pixels 2 showing the modificationof the pixel structure according to the third embodiment. In FIG. 17,the parts corresponding to FIG. 14 are denoted with the same referencenumerals, and the description about those parts is omitted as necessary.

In the modification of third embodiment shown in FIG. 17, an on-chiplens 161A corresponding to the on-chip lens 48 in FIG. 14 and a secondwall 161B corresponding to the second wall 100 in FIG. 14 are formed byusing the same on-chip lens material.

For example, as shown in FIG. 17, an organic material or an inorganicmaterial having a refractive index of about 1.60 is used as a materialof the on-chip lens 161A and the second wall 161B. In addition, thesecond low refractive index film 45, the first low refractive index film44, and the light shielding film 43 of the first wall 50 are formed tohave the refractive indexes of about 1.6, about 1.7, and about 2.7,respectively. The color filter 47 and the high refractive index layer141 are formed to have the refractive indexes of about 1.5 and about1.8, respectively.

Therefore, the first wall 50 and the second wall 161B are formed suchthat the refractive index is the same or the refractive index increasessequentially from the on-chip lens 48 to the semiconductor substrate 12.

In the second wall 161B, it is sufficient that a refractive indexdifference from the adjacent layer is generated so that the refractiveindex is lower than that of the adjacent layer (the high refractiveindex layer 141 in the present embodiment), and therefore, the on-chiplens 161A and the second wall 161B can be formed using the same on-chiplens material as described above in the case where the high refractiveindex layer 141 is adopted in the upper portion of the color filter 47.

<12. Actions and Effects of First Wall and Second Wall>

FIG. 18 shows optical simulation results verified by comparing the pixelstructures of the above first and second embodiments with the pixelstructure where only the inter-pixel light shielding film 301 shown inFIG. 1 is formed.

The graph of FIG. 18 shows approximate straight lines L1 to L3indicating the relationship between sensitivity level and color mixinglevel in each of the pixel structure of the first embodiment in whichonly the first wall 50 is formed, the pixel structure of the secondembodiment in which both of the first wall 50 and the second wall 100are formed, and the pixel structure of FIG. 1 in which only theinter-pixel light shielding film 301 is formed. The horizontal axis ofthe graph in FIG. 18 represents the sensitivity level and the verticalaxis represents the color mixing level.

The approximate straight line L1 is an approximate straight line basedon plotting the sensitivity level and color mixing level by changing therefractive indexes of the first low refractive index film 44 and thesecond low refractive index film 45 of the first wall 50 in the pixelstructure of the first embodiment in which only the first wall 50 isformed.

The approximate straight line L2 is an approximate straight line basedon plotting the sensitivity level and color mixing level by changing therefractive indexes of the first low refractive index film 44, the secondlow refractive index film 45, and the second wall 100 in the pixelstructure of the second embodiment in which both of the first wall 50and the second wall 100 are formed.

The approximate straight line L3 is an approximate straight line basedon plotting the sensitivity level and color mixing level by changing theheight of the inter-pixel light shielding film 301 in the pixelstructure of FIG. 1.

It should be noted that a plot P1 used for the calculation of theapproximate straight line L1, a plot P2 used for calculating theapproximate straight line L2, and a plot P3 used for calculating theapproximate straight line L3 are optical simulation results in a casewhere the height of the light shielding film 43 of the first wall 50 andthe height of the inter-pixel light shielding film 301 are set to thesame condition of 280 nm.

As can be seen from FIG. 18, in the pixel structure where only theinter-pixel light shielding film 301 is formed, when the height of theinter-pixel light shielding film 301 is increased, color mixing can besuppressed but the sensitivity is greatly reduced.

On the other hand, according to the pixel structure of the firstembodiment in which the first low refractive index film 44 and thesecond low refractive index film 45 of the low refractive index materialare provided on the light shielding film 43, the sensitivity can beimproved and the color mixing can be reduced as compared with the casewhere only the inter-pixel light shielding film 301 is provided.

In addition, the pixel structure of the second embodiment furtherprovided with the second wall 100 can also improve the sensitivity andreduce the color mixing as compared with the case where only theinter-pixel light shielding film 301 is provided. In the comparisonbetween the first embodiment and the second embodiment, although thesecond embodiment is slightly lower than the first embodiment regardingthe sensitivity level, the color mixing level is significantly improvedin the second embodiment than in the first embodiment.

Therefore, according to the pixel structures of the first to thirdembodiments to which the present technology is applied, it is possibleto increase the condensing efficiency of pixels, and it is possible toreduce leakage of oblique light to adjacent pixels. That is, whileimproving color mixing, the sensitivity can be improved. Therefore,there is no need to perform extreme pupil correction, and robustnessagainst the lens position shift can be achieved. By reducing thecorrection amount of pupil correction, the coloring phenomenon of imagesensor chip periphery due to color mixing can also be improved.

<13. Application Example to Electronic Device>

The present technology is not limited to application to solid-stateimaging devices. That is, the present technology can be applied to allelectronic devices using a solid-state imaging device for an imagecapturing unit (photoelectric conversion unit) such as imaging devicessuch as digital still cameras and video cameras, portable terminaldevices having imaging functions, copying machines using solid-stateimaging devices for image reading units, and the like. The solid-stateimaging device may be in a form formed as a single chip or in a modularform having an imaging function in which the imaging unit and the signalprocessing unit or the optical system are packaged together.

FIG. 19 is a block diagram showing the configuration example of theimaging device as an electronic device to which the present technologyis applied.

An imaging device 200 in FIG. 19 includes an optical unit 201 includinga lens group and the like, a solid-state imaging device (imaging device)202 in which the configuration of the solid-state imaging device 1 inFIG. 4 is employed, and a DSP (Digital Signal Processor) circuit 203which is a camera signal processing circuit. In addition, the imagingdevice 200 also includes a frame memory 204, a display unit 205, arecording unit 206, an operation unit 207, and a power supply unit 208.The DSP circuit 203, the frame memory 204, the display unit 205, therecording unit 206, the operation unit 207, and the power supply unit208 are connected to each other via a bus line 209.

The optical unit 201 captures incident light (image light) from theobject and forms an image on the imaging surface of the solid-stateimaging device 202. The solid-state imaging device 202 converts thelight amount of the incident light imaged on the imaging surface by theoptical unit 201 into electric signals in pixel units and outputs theelectric signals as pixel signals. The solid-state imaging device 1 ofFIG. 4 can be used as this solid-state imaging device 202, and morespecifically, the solid-state imaging device having the pixel structureof the first embodiment having the first wall 50 including the first lowrefractive index film 44 and the second low refractive index film 45 ofthe low refractive index material or the pixel structure of the secondembodiment or the third embodiment including the first wall 50 and thesecond wall 100 can be used as this solid-state imaging device 202.

The display unit 205 includes a panel type display device such as aliquid crystal panel or an organic EL (Electro Luminescence) panel, forexample, and displays a moving image or a still image imaged by thesolid-state imaging device 202. The recording unit 206 records themoving image or the still image imaged by the solid-state imaging device202 on a recording medium such as a hard disk or a semiconductor memory.

The operation unit 207 issues an operation command for various functionsof the imaging device 200 under user's operation. The power supply unit208 appropriately supplies various power supplies serving as operationpower sources for the DSP circuit 203, the frame memory 204, the displayunit 205, the recording unit 206, and the operation unit 207 to thesesupply targets.

As described above, by using the solid-state imaging device 1 having thepixel structure of any one of the aforementioned first to thirdembodiments as the solid-state imaging device 202, it is possible toimprove the sensitivity and greatly reduce the color mixing. Therefore,even in the imaging device 200 for such as a video camera, a digitalstill camera, and furthermore a camera module for a mobile device suchas a cellular phone, the imaging quality of the imaging image can beimproved.

<Usage Example of Image Sensor>

FIG. 20 shows an example of use in which the solid-state imaging device1 described above is used as an image sensor.

The image sensor using the above-described configuration of thesolid-state imaging device 1 can be used for various cases of sensinglight such as, visible light, infrared rays, ultraviolet light, X rays,and the like as follows.

A digital camera, a mobile device with a camera function, and the liketo take pictures which are to be viewed

Device provided for the use in relation to traffic such as an in-vehiclesensor for imaging, e.g., the front, the back, the periphery, and theinside of an automobile for safe driving such as automatic stop andrecognition of the state of the driver and the like, a surveillancecamera for monitoring traveling vehicles and roads, a distance measuringsensor for distance measurement of a distance between vehicles and thelike

Devices provided for the use in relation to home electronics of a TV, arefrigerator, an air conditioner, and the like in order to photograph auser's gesture and operate the equipment according to the gesture

Devices provided for the use in relation to medical care and health caresuch as endoscope and device for performing angiography by receivinginfrared rays

Devices provided for the use in relation to security such assurveillance cameras for security applications, and cameras for personauthentication usage

Devices provided for the use in relation to cosmetic purposes such asskin measuring devices for photographing the skin, and microscopes forphotographing the scalp

Devices provided for the use in relation to sports and the like such asaction camera for sports usage, and wearable cameras

Devices provided for the use in relation to agriculture such as camerasfor monitoring the condition of fields and crops

In the above example, the solid-state imaging device in which the firstconductivity type is P type, the second conductivity type is N type, andelectrons are signal charges has been described, but the presenttechnology can also be applied to solid-state imaging devices in whichholes are signal charges. In other words, the first conductivity typemay be N type, and the second conductivity type may be P type, so thatthe aforementioned semiconductor regions include semiconductor regionsof opposite conductivity types.

In addition, the present technology is not limited to application to thesolid-state imaging device that detects the distribution of the amountof incident light of visible light and captures the distribution as animage. The present technology can be applied to solid-state imagingdevices (physical quantity distribution detection devices) in generalsuch as a solid-state imaging device that images the distribution of theincident amount of infrared rays, X-rays, particles or the like as animage, and, as a meaning in a broad sense, a fingerprint detectionsensor or the like for detecting the distribution of other physicalquantities such as pressure and electrostatic capacity and capturing thedistribution as an image.

In addition, the present technology is applicable not only tosolid-state imaging devices but also to all semiconductor devices havingother semiconductor integrated circuits in general.

The embodiment of the present technology is not limited to theabove-described embodiments, and various modifications are possiblewithout departing from the gist of the present technology.

For example, it is possible to adopt a form in which all or some of theabove-described plurality of embodiments are combined.

For example, in the first embodiment described above, the height of thefirst wall 50 is made substantially equal to the height of the colorfilter 47, and in the second embodiment, the height of the second wall100 is made substantially the same as the height of the high refractiveindex layer 141, but the height of the first wall 50 and the height ofthe second wall 100 do not necessarily have to match the height of thecolor filter 47 or the height of the high refractive index layer 141.For example, the height of the first wall 50 may be lower than theheight of the color filter 47, and the thickness (height) of the secondwall 100 may be formed to be thick accordingly. In other words, in thepixel structure of the present technology, at least one layer of pixelisolation wall is formed on the light shielding film 43 arranged at thepixel boundary, and it is only necessary that the refractive index ofeach layer of the one or more layers of the pixel isolation wall isformed to have a refractive index that is lower than the light shieldingfilm 43 and that increases sequentially from the on-chip lens 48 to thesemiconductor substrate 12.

The effects described in this specification are merely examples and arenot intended to be limiting, and may have effects other than thosedescribed in the present specification.

It should be noted that the present technology can also have thefollowing configuration.

(1)

A solid-state imaging device including a first wall provided between apixel and a pixel arranged two-dimensionally to isolate the pixels,

in which the first wall includes at least two layers including a lightshielding film of a lowermost layer and a low refractive index film ofwhich refractive index is lower than the light shielding film.

(2)

The solid-state imaging device according to (1), in which the lightshielding film includes a metal film.

(3)

The solid-state imaging device according to (1) or (2), in which the lowrefractive index film includes a laminated layer including a first lowrefractive index film and a second low refractive index film, and

a refractive index increases in a following order: the second lowrefractive index film, the first low refractive index film which isbelow the second low refractive index film, and the light shielding filmwhich is the lowermost layer.

(4)

The solid-state imaging device according to (3), in which the first lowrefractive index film and the second low refractive index film includean inorganic film or an organic film.

(5)

The solid-state imaging device according to any one of (1) to (4), inwhich the first wall is formed to have the same height as an adjacentcolor filter.

(6)

The solid-state imaging device according to any one of (1) to (5), inwhich the first wall is covered with a protective film to preventcorrosion.

(7)

The solid-state imaging device according to any one of (1) to (6),further including a second wall provided at an upper side of the firstwall to isolate the pixels.

(8)

The solid-state imaging device according to (7), in which the secondwall is provided between the on-chip lens of the pixels.

(9)

The solid-state imaging device according to (7) or (8), in which a crosssectional shape of the second wall is a reverse trapezoidal shape havinga thinner bottom width than a top width.

(10)

The solid-state imaging device according to any one of (7) to (9), inwhich the second wall includes an inorganic film or an organic film.

(11)

The solid-state imaging device according to any one of (7) to (10), inwhich a refractive index of the second wall is lower than a refractiveindex of an adjacent layer.

(12)

The solid-state imaging device according to any one of (7) to (11), inwhich the second wall is formed using the same material as the on-chiplens.

(13)

The solid-state imaging device according to any one of (1) to (12), inwhich a refractive index of the on-chip lens is in a range of 1.60 to2.00.

(14)

The solid-state imaging device according to any one of (1) to (13), inwhich in each pixel, a color filter, a high refractive index layer, andan on-chip lens are layered in this order on an upper side of aphotoelectric conversion unit formed on a semiconductor substrate, and

the color filter, the high refractive index layer, and the on-chip lensare formed to have refractive indexes that increase from thesemiconductor substrate to the on-chip lens.

(15)

A manufacturing method of a solid-state imaging device, in which a firstwall is formed between a pixel and a pixel arranged two-dimensionally toisolate the pixels, and

the first wall includes at least two layers including a light shieldingfilm of a lowermost layer and a low refractive index film of whichrefractive index is lower than the light shielding film.

(16)

An electronic device including a solid-state imaging device including afirst wall provided between a pixel and a pixel arrangedtwo-dimensionally to isolate the pixels,

in which the first wall includes at least two layers including alightshielding film of a lowermost layer and a low refractive index film ofwhich refractive index is lower than the light shielding film.

REFERENCE SIGNS LIST

-   PD photodiode-   1 solid-state imaging device-   2 pixel-   3 pixel array unit-   12 semiconductor substrate-   43 light shielding film-   44 first low refractive index film-   45 second low refractive index film-   46 protective film-   47 color filter-   48 on-chip lens-   49 antireflection film-   50 first wall-   100 second wall-   141 high refractive index layer-   161A on-chip lens-   161B second wall-   200 imaging device-   202 solid-state imaging device

1. A solid-state imaging device comprising a first wall provided betweena pixel and a pixel arranged two-dimensionally to isolate the pixels,wherein the first wall includes at least two layers including a lightshielding film of a lowermost layer and a low refractive index film ofwhich refractive index is lower than the light shielding film.
 2. Thesolid-state imaging device according to claim 1, wherein the lightshielding film includes a metal film.
 3. The solid-state imaging deviceaccording to claim 1, wherein the low refractive index film includes alaminated layer including a first low refractive index film and a secondlow refractive index film, and a refractive index increases in afollowing order: the second low refractive index film, the first lowrefractive index film which is below the second low refractive indexfilm, and the light shielding film which is the lowermost layer.
 4. Thesolid-state imaging device according to claim 3, wherein the first lowrefractive index film and the second low refractive index film includean inorganic film or an organic film.
 5. The solid-state imaging deviceaccording to claim 1, wherein the first wall is formed to have a sameheight as an adjacent color filter.
 6. The solid-state imaging deviceaccording to claim 1, wherein the first wall is covered with aprotective film to prevent corrosion.
 7. The solid-state imaging deviceaccording to claim 1, further comprising a second wall provided at anupper side of the first wall to isolate the pixels.
 8. The solid-stateimaging device according to claim 7, wherein the second wall is providedbetween the on-chip lens of the pixels.
 9. The solid-state imagingdevice according to claim 7, wherein a cross sectional shape of thesecond wall is a reverse trapezoidal shape having a thinner bottom widththan a top width.
 10. The solid-state imaging device according to claim7, wherein the second wall includes an inorganic film or an organicfilm.
 11. The solid-state imaging device according to claim 7, wherein arefractive index of the second wall is lower than a refractive index ofan adjacent layer.
 12. The solid-state imaging device according to claim7, wherein the second wall is formed using a same material as theon-chip lens.
 13. The solid-state imaging device according to claim 1,wherein a refractive index of the on-chip lens is in a range of 1.60 to2.00.
 14. The solid-state imaging device according to claim 1, whereinin each pixel, a color filter, a high refractive index layer, and anon-chip lens are layered in this order on an upper side of aphotoelectric conversion unit formed on a semiconductor substrate, andthe color filter, the high refractive index layer, and the on-chip lensare formed to have refractive indexes that increase from thesemiconductor substrate to the on-chip lens.
 15. A manufacturing methodof a solid-state imaging device, wherein a first wall is formed betweena pixel and a pixel arranged two-dimensionally to isolate the pixels,and the first wall includes at least two layers including a lightshielding film of a lowermost layer and a low refractive index film ofwhich refractive index is lower than the light shielding film.
 16. Anelectronic device comprising a solid-state imaging device including afirst wall provided between a pixel and a pixel arrangedtwo-dimensionally to isolate the pixels, wherein the first wall includesat least two layers including alight shielding film of a lowermost layerand a low refractive index film of which refractive index is lower thanthe light shielding film.